Beginner
10 min

Strive for perfection in your projects using AD5142A and ATmega2560

Say goodbye to analog limitations

DIGI POT 12 Click with Arduino Mega 2560 Rev3

Published Feb 14, 2024

Click board™

DIGI POT 12 Click

Dev. board

Arduino Mega 2560 Rev3

Compiler

NECTO Studio

MCU

ATmega2560

Maximize the potential of your electronic circuits by unlocking unparalleled precision with our digital potentiometer – the key to achieving peak performance and efficiency in every application.

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Hardware Overview

How does it work?

DIGI POT 12 Click is based on the AD5142A, a dual-channel, 256-position nonvolatile digital potentiometer from Analog Devices. The resistor wiper position is determined by the RDAC register contents, which act as a scratchpad register, allowing unlimited changes of resistance settings. The scratchpad register can be programmed with any position setting using the standard I2C interface by loading the 16-bit data word. The nominal resistance of the RDAC between terminals A and terminals B (RAB) is 10KΩ with 8-bit RDAC latch data decoded to select one of the 256 possible wiper settings. When a desired position is found, this value can be stored in the onboard EEPROM memory; thus, the wiper position is always restored for subsequent power-ups. The EEPROM data can be read back, written

independently, and protected by software. This Click board™ communicates with MCU through a standard 2-Wire I2C interface and operates at Standard (100KHz) and Fast (400KHz) data transfer modes. The I2C address can be selected via the ADDR SEL jumpers with 0 selected by default. There is an RST pin for resetting the digital potentiometers RDAC registers from EEPROM, with active LOW logic. In addition, this Click board™ comes with the INDEP SEL jumper that allows you to choose between the potentiometer and the linear gain setting mode, with the potentiometer mode set by default (0). The linear gain setting mode of operation can control the potentiometer as two independent rheostats connected at a single point. Once the jumper is set, it can not be turned off by software. In

addition, there is a burst mode in which multiple data bytes can be sent to the host MCU. The Shutdown mode places the RDAC in a zero power consumption while the data in EEPROM remains. There is no polarity constraint between the B, W, and A on both terminals, but they can not be higher than the VCC (5V maximum) nor lower than the VSS (0V). This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

DIGI POT 12 Click hardware overview image

Features overview

Development board

Arduino Mega 2560 is a robust microcontroller platform built around the ATmega 2560 chip. It has extensive capabilities and boasts 54 digital input/output pins, including 15 PWM outputs, 16 analog inputs, and 4 UARTs. With a 16MHz crystal

oscillator ensuring precise timing, it offers seamless connectivity via USB, a convenient power jack, an ICSP header, and a reset button. This all-inclusive board simplifies microcontroller projects; connect it to your computer via USB or power it up

using an AC-to-DC adapter or battery. Notably, the Mega 2560 maintains compatibility with a wide range of shields crafted for the Uno, Duemilanove, or Diecimila boards, ensuring versatility and ease of integration.

Arduino Mega 2560 Rev3 double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

AVR

MCU Memory (KB)

256

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

8192

You complete me!

Accessories

Click Shield for Arduino Mega comes equipped with four mikroBUS™ sockets, with two in the form of a Shuttle connector, allowing all the Click board™ devices to be interfaced with the Arduino Mega board with no effort. Featuring an AVR 8-bit microcontroller with advanced RISC architecture, 54 digital I/O pins, and Arduino™ compatibility, the Arduino Mega board offers limitless possibilities for prototyping and creating diverse applications. This board is controlled and powered conveniently through a USB connection to program and debug the Arduino Mega board efficiently out of the box, with an additional USB cable connected to the USB B port on the board. Simplify your project development with the integrated ATmega16U2 programmer and unleash creativity using the extensive I/O options and expansion capabilities. There are eight switches, which you can use as inputs, and eight LEDs, which can be used as outputs of the MEGA2560. In addition, the shield features the MCP1501, a high-precision buffered voltage reference from Microchip. This reference is selected by default over the EXT REF jumper at the bottom of the board. You can choose an external one, as you would usually do with an Arduino Mega board. There is also a GND hook for testing purposes. Four additional LEDs are PWR, LED (standard pin D13), RX, and TX LEDs connected to UART1 (mikroBUS™ 1 socket). This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino Mega board with Click Shield for Arduino Mega, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Click Shield for Arduino Mega accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Reset
PL1
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PD0
SCL
I2C Data
PD1
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

DIGI POT 12 Click Schematic schematic

Step by step

Project assembly

Click Shield for Arduino Mega front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino Mega 2560 Rev3 as your development board.

Click Shield for Arduino Mega front image hardware assembly
Arduino Mega 2560 Rev3 front image hardware assembly
Charger 27 Click front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Board mapper by product8 hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Arduino MEGA MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

This library contains API for DIGI POT 12 Click driver.

Key functions:

  • digipot12_set_resistance - DIGI POT 12 set the resistance function.

  • digipot12_get_resistance - DIGI POT 12 get the resistance function.

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief DIGI POT 12 Click example
 *
 * # Description
 * This library contains API for DIGI POT 12 Click driver.
 * The demo application uses a digital potentiometer 
 * to change the resistance values of both channels.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * The initialization of I2C module, log UART, and additional pins.
 * After the driver init, the app executes a default configuration.
 *
 * ## Application Task
 * This example demonstrates the use of the DIGI POT 12 Click board™.
 * The demo application iterates through the entire wiper range and 
 * sets the resistance of both channels in steps of approximately 1kOhm.
 * Results are being sent to the UART Terminal, where you can track their changes.
 *
 * @author Nenad Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "digipot12.h"

static digipot12_t digipot12;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    digipot12_cfg_t digipot12_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    digipot12_cfg_setup( &digipot12_cfg );
    DIGIPOT12_MAP_MIKROBUS( digipot12_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == digipot12_init( &digipot12, &digipot12_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( DIGIPOT12_ERROR == digipot12_default_cfg ( &digipot12 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
    log_printf( &logger, " ----------------------------\r\n" );
    Delay_ms ( 100 );
}

void application_task ( void ) 
{
    static float res_kohm;
    for ( uint8_t n_cnt = DIGIPOT12_RES_0_KOHM; n_cnt <= DIGIPOT12_RES_10_KOHM; n_cnt++ )
    {
        if ( DIGIPOT12_OK == digipot12_set_resistance( &digipot12, DIGIPOT12_WIPER_SEL_1, ( float ) n_cnt ) )
        {
            if ( DIGIPOT12_OK == digipot12_get_resistance( &digipot12, DIGIPOT12_WIPER_SEL_1, &res_kohm ) )
            {
                log_printf( &logger, " Rwb1 : %.2f kOhm\r\n", res_kohm );
                Delay_ms ( 100 );
            }
        }
        
        if ( DIGIPOT12_OK == digipot12_set_resistance( &digipot12, DIGIPOT12_WIPER_SEL_2, ( float ) ( DIGIPOT12_RES_10_KOHM - n_cnt ) ) )
        {
            if ( DIGIPOT12_OK == digipot12_get_resistance( &digipot12, DIGIPOT12_WIPER_SEL_2, &res_kohm ) )
            {
                log_printf( &logger, " Rwb2 : %.2f kOhm\r\n", res_kohm );
                Delay_ms ( 100 );
            }
        }
        log_printf( &logger, " ----------------------------\r\n" );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
    }
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END

Additional Support

Resources

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